The use of devices implanted in the body to supplement or even supplant the operation of the body's own natural organs has expanded dramatically in recent times. An essential component of the implanted devices has been, and continues to be, the power source supplying energy to the device.
Early efforts in the area of artificially supplementing or supplanting body functions were directed toward regulating the rhythmic beating of an otherwise healthy heart. Stimulating units which operated at specified beat rates, known as pacemakers, were surgically implanted into the body and attached to the heart. On a signal from the pacemaker, the heart would contract and thereby pump blood through the circulatory system. Power for the pacemaker was supplied by a battery having long operating duration, the battery being implanted under the skin. Replacement of this battery required further surgery.
The pacemaker could substantially restore a normal life-style to a patient having a fundamentally sound, yet irregularly beating heart. However, for those having a damaged, defective or diseased heart, until recently the options were limited to either a regimen of bed rest and medication or heart transplant.
A significant recent advance in heart care has been the development of an artificial heart. The artificial heart functions as a total replacement for the natural organ, and recently was shown to provide many additional months of life to a man who otherwise would not have lived. However, the total artificial heart presently requires so much peripheral support equipment as to make the recipient a virtual prisoner to that equipment.
Where the heart is still able to function but yet is inadequate to handle the demands of normal activities, mechanical devices are now available to assist the function of the natural organ. These devices, known as ventricular assist systems, improved the ability of the natural heart to pump oxygenated blood to the rest of the body. The assist systems augment the natural heart by assuming the pumping function of the left ventricle, thereby forcing oxygenated blood from the ventricle through the body's circulatory system.
Systems have been developed having a peripheral power source which fits inside a carrying case having a shoulder strap, permitting the user of the assist system a larger degree of mobility. The power source is rechargeable and easily replaceable, as a practical concession to the requirement that the source be both portable and yet capable of supplying the relatively large power consumption requirements of the implanted device. The implanted assist device is connected to the peripheral equipment by means of a cable bundle running from the implanted system through the skin to the outside. The use of the portable power supply restores the wearer to a nearly normal level of mobility. However, the portable power supply requires that the wearer constantly carry it with him. Further, the cable bundle running through the skin must be handled with extreme care to minimize the possibility of infection or of damage to the skin and underlying tissues in proximity to the bundle. Also the cable bundle is relatively bulky, imposes an unnatural appearance on the body, and requires that caution be exercised when clothes are worn over the bundle.